(1) Field of the Invention
The present invention relates generally to electric motors and, more particularly, to an electric motor having a construction which takes advantage of the principles of magnetic attraction and repulsion to cause the rotor of the motor to roll within the motor stator by contact and thereafter repulsion between the rotor and the stator.
(2) Description of the Prior Art
Conventional electric motors operable to convert electrical energy into mechanical energy are well known. Because of their many advantages, electric motors have largely replaced other motive power in industry, transportation, mines, business, farms and homes. Electric motors are convenient, economical to operate, inexpensive to purchase, safe, free from smoke and odor and comparatively quiet. They can meet a wide range of service requirements, such as, starting, accelerating, running, braking, holding and stopping a load. They are available in sizes from a small fraction of a horsepower to many thousands of horsepower, and in a wide range of speeds. The speed may be fixed or synchronous, constant for given load conditions, adjustable or variable. Many are self-starting and reversible.
Electric motors may either be of the alternating-current or direct-current variety. Although alternating-current motors are more common, direct-current motors are unexcelled for applications requiring simple, inexpensive speed control or sustained high torque under low-voltage conditions.
The construction and theory of operation of conventional electric motors are well known. In a conventional electric motor, a rotor is positioned within the motor housing and has a central shaft which is fixed at its ends in bearings retained within the housing. With this arrangement, electromagnetic interaction between the rotor and the stator positioned at the inside wall of the motor housing and surrounding the rotor causes the rotor to rotate about the central shaft.
While the conventional electric motor in use today certainly performs satisfactorily over a wide range of applications, it is not without problems. For example, the inefficiency inherent with motor stator end turns results in less than optimum motor horsepower to weight and motor horsepower to volume ratios. As a result, conventional electric motors must be physically sized larger than they would otherwise be if these ratios could be optimized.
Consequently, there is a need for an alternative design electric motor which optimizes these motor horsepower to weight and motor horsepower to volume design ratios and therefore may be used in applications in which horsepower, weight and volume considerations are all of critical importance.
The present invention is directed to a roller-type electric motor designed to satisfy the aforementioned need. The roller-type motor of the present invention has a construction which makes it particularly useful for high torque, low revolutions-per-minute applications. The speed reduction inherent in the motors"" power removal scheme and the motor winding direction significantly improves its horsepower to weight and horsepower to volume ratios. The major difference between the electric motor of the present invention and a conventional electric motor is that the moving part of this electric motor, which would be considered the rotor of a conventional motor, does not rotate about a shaft centered in the cylinder formed by the stator and is not drawn to rotate past the poles of the stator by alternately switching the polarity of the poles of the stator. In the electric motor of the present invention, the rotor or moving part xe2x80x9crollsxe2x80x9d on the inside of the stator, and its motion is like that of a barrel rolling inside of another barrel.
Accordingly, the present invention is directed to a roller-type electric motor which includes: (a) a housing having a hollow interior and an inner wall; (b) a first plurality of stator poles each of predetermined magnetic polarity and positioned at the inner wall of the housing; (c) a roller having an outer surface and positioned for rolling movement within the hollow interior of the housing; (d) a second plurality of roller poles each of predetermined magnetic polarity and positioned on the outer surface of the roller, one of the second plurality of roller poles having a magnetic polarity opposite the magnetic polarity of one of the first plurality of stator poles so that the first roller pole is drawn through magnetic action into contact with the first stator pole; and (e) a control device for reversing the magnetic polarity of the first stator pole when the first roller pole is in contact therewith to repel through magnetic action the first roller pole while simultaneously predetermined roller poles adjacent to the first roller pole are magnetically drawn towards predetermined stator poles adjacent to the first stator pole and thereby impart rolling movement to the roller within the housing.
These and other advantages and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawing wherein there is shown and described illustrative embodiments of the invention.